Hypertension is a major risk factor for cardiovascular and renal disease, and a leading cause of premature mortality worldwide. Early hypertension studies showed that treating elevated blood pressure (BP) reduces patients' risk of cardiovascular disease and all-cause mortality. In subsequent research, patients achieved greater improvement in cardiovascular outcomes when their treatment was aimed at a moderate systolic BP target (<150mmHg) than at higher targets. Although observational data suggest that even lower BP targets may be beneficial, this has not been seen in randomized trials; instead, "intense" treatment of hypertension (i.e., to a target systolic BP <120mmHg) was found to have no effect on participants' risk for renal disease, cardiovascular disease, or all-cause mortality.

One potential explanation for this apparent lack of benefit of intense BP targets is that the study protocols targeted reductions in clinic BP rather than ambulatory BP. Ambulatory BP monitoring (ABPM) allows for assessment of BP throughout the day and night. Of all the BP measurements, nighttime systolic BP appears to be the best predictor of cardiovascular disease and all-cause mortality. Because recent trials assessing intense BP targets did not include ambulatory BP measurements, the effect of intensive treatment on nighttime BP is largely unknown.

To address this important gap in knowledge, we will conduct ABPM in 600 participants as part of an ancillary study to the ongoing Systolic Blood Pressure Intervention Trial (SPRINT). The goal of the ancillary study is to evaluate the effect of intensive vs. standard clinic based BP targets on nighttime BP (primary outcome), as well as night/day BP ratio, timing of peak BP, 24hr BP, and BP variability (secondary outcomes). The SPRINT trial includes approximately 9250 participants at high risk for cardiovascular disease.

The investigators hypothesize that intense targeting of clinic systolic BP does not lower nighttime systolic BP compared to a standard target.

Ambulatory blood pressure monitoring will be performed within 3 weeks of the 27 month follow up visit. For the primary analysis, nighttime BP will be defined by narrow clock time (01:00 AM to 6:00 AM).

Ambulatory blood pressure monitoring will be performed within 3 weeks of the 27 month follow up visit. The timing of the peak BP will be calculated for each subject using cosinor rhythmometry analysis.

Ambulatory blood pressure monitoring will be performed within 3 weeks of the 27 month follow up visit. Blood pressure variability will be defined by the standard deviation of the systolic blood pressure and by calculating the average real variability (ARV).

Participants randomized into the Intensive BP arm will have a goal of SBP <120mmHg. Drugs will be added and/or titrated at each visit (monthly) to achieve SBP <120 mmHg. At periodic "milepost" visits, addition of another drug will be "required" if not at goal.

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Please refer to this study by its ClinicalTrials.gov identifier: NCT01835249